170 Agricultural Gazette. 



2. T. Schachtii, Schmidt. V 'H Z^ e' » . «"•»• is the formula* for the 

 freshly hatched larva?, of which the following is a further description : — 

 Neck cylindroid to opposite the base of the spear, tlienco convex-conoid to 

 the rather narrow but unusually prominent and projecting lip region ; spear 

 bulbed at its base ; anterior part of the oesophagus a narrow chitinous 

 canal, which leads to a muscular prolate bulb two-thirds as wide as the 

 adjacent part of the neck ; nerve-ring close behind the bulb just mentioned ; 

 remainder of the (esophagus apparently indistinct, certainly short ; intestine 

 three-fourths as wide as the body, terminating posteriorly in a rectum one- 

 third as long as the anal diameter; tail conical ; rudimentary sexual appa- 

 ratus a little in front of the commencement of the 2)osterior third of the 

 body. 



The larva?, which are found in the soil, make their way into rootlets of 

 various plants by means of the special piercing and sucking apparatus (spear 

 and bulb), and then undergo a remarkable metamorphosis, similar to that 

 already described in the case of T. arenariiis, Neal. At an early moult they lose 

 the conical tail, a shorter and rounded one taking its place. Meanwhile the 

 body, amply nourished by plant juices, becomes plump, and takes on the 

 dimensions shown in the following formula: — ^|? — "J).] — .; — j^?i — ^. 



The sexual organs now begin to develop, and the larva; become elongated 

 sac-shaped. The female continues to develop in this manner, and becomes 

 finally a motionless, widely fusiform sac, devoid of anus and with a terminal 

 vulva. The two-parted female sexual a])paratus develops enormously, and 

 at last fills the body of the worm completely. The number of eggs con- 

 tained in it averages 300 to 400. These are deposited in the tissue of the 

 plant attacked at a period when they contain well-developed embryos. The 

 male, however, instead of continuing in the path of development followed by 

 the female, returns to a slender form, having the following dimensions : — 

 'i- — ^F — '^r — J- — TT- The .structure of the head and oesophagus is quite 

 similar to that of the newly-hatched larva). The tail, however, becomes 

 nearly hemispherical. The linear-cuneiform spicula are arcuate and acute. 

 There is no bursa and the testicle extends to the middle of the body at 

 least. The change of the male to the slender form occupies at least five or 

 six days. Nothing is known concerning the copulation. The eggs laid by 

 the female are '04 x '08 mm. The males and females arc born in equal 

 numbers, and the change from the egg to the adult state occupies from five 

 to six weeks. 



This worm is the cause of a most serious disease in the sugar-beet. Por 

 remedies, see those recommended for T. arenariiis. 



3. T. arenarius, Neal. SufSciently described in the foregoing pages. 

 Por remedies, sec section III. 



4. T. robustus, De Man. 1 ^ ? '°;» f^^ "f r7mm. Ciiticula finely striated ; 

 heterocephalous, lipless ; two lateral and four aubmedian chitinous edges 

 (soon disappearing) found on the head ; spear very .stout ; median bulb 

 ovate ; portis cxcretorius, at ten per cent. 



"T — ?' — ^r — i^ — T^ 1-3 mm. Neck, as in the female, diminishing considerably ; 

 tail completely enveloped by the bursa, which presents two lateral papilla; 

 on the post-anal part ; the short spicula accompanied by rod-shaped acces- 

 sory pieces. 



This slow moving species is rather common in Holland, in soil penetrated 

 by fresh or brackish water. 



* For an explanation of the formulie used in this report sec tlie fii-st number of tliis Gazette, p. 131. 



